The NFL has acknowledged that referees made a mistake in not penalizing the San Diego Chargers for an illegal formation on a missed field goal attempt by Ryan Succop of the Kansas City Chiefs.

Succop missed a 41-yard field goal, but the Chargers were in an illegal formation that should have resulted in a five-yard penalty and another field goal attempt.

"On the play, San Diego lined up with seven men on one side of the snapper," the league said in a statement released Monday morning. "This should have been penalized as an illegal formation by the defense."

The Chargers eventually won the game to secure the final AFC playoff bid, but the Pittsburgh Steelers would have advanced had the penalty been called and Succop made the second attempt.